Memory is a spectrum. Working memory is the active context window. Semantic memory holds distilled facts. Episodic memory records what happened and when. Procedural memory holds reusable skills and rules (CLAUDE.md, slash commands, skill packs).

This lesson maps that spectrum so you choose the right mechanism for what your system needs to remember and for how long. Do not run cosine search over episodic logs when you need time and identity filters.